As a heat sink of this type, conventionally, a heat sink including a supporting plate that makes close contact with and is fixed to a cooling target object and is made of a material having excellent heat conductivity, and a plurality of plate-like, columnar, or cylindrical fins that are provided on the supporting plate in a standing manner and are made of a material having excellent heat conductivity has been provided (for example, see Patent Documents 1 and 2). The disclosed heat sink is configured to dissipate heat transferred to the supporting plate from the cooling target object into the air through the surfaces of the fins. For example, in recent years, light-emitting diode (LED) lighting has been widely spread and high-output LED lighting such as lighting for a warehouse has been provided. Increase in output increases a heat generation amount and further improvement in heat dissipation performance of the heat sink is therefore required in order to protect LED elements of which lifetime is easy to be shorten with heat.
In order to improve the heat dissipation performance of the heat sink while avoiding increase in size thereof, the number of fins can be increased. The increase in the number of fins increases a heat dissipation area, so that improvement in the heat dissipation performance can be expected. However, the increase in the number of fins lowers strength of the supporting plate supporting the fins and thereby lowers strength for supporting the fins, resulting in a problem. Further, when the fins are crowded, hot air is accumulated between the fins. In particular, the hot air is accumulated near the supporting plate at the base end side and heat absorbing performance from the cooling target object also lowers. This causes certain limitation on the improvement in the heat dissipation performance. An air blower such as a fan can be separately provided so as to forcibly dissipate the hot air between the fins but it is limited. The air blower cannot be provided in some heat sinks because of increase in weight, space, and the like.